Methods for removing bitumen from tar sands

ABSTRACT

Methods are provided for removing bitumen from tar sands. One method may include contacting the tar sands with a hydrocarbon. The method may also include contacting the tar sands including the hydrocarbon with a water soluble silicate. The method may further include separating the tar sands into a liquid portion and a solid portion, the liquid portion including the water soluble silicate and the bitumen. The method may also include separating the water soluble silicate from the bitumen.

BACKGROUND

A large amount of the world's oil supply may be found in tar sands. Tar sands, commonly referred to as “oil sands”, are generally a combination of clay, sand, water, and bitumen, which is a highly viscous mixture including hydrocarbons. Tar sands can be mined and processed to extract the bitumen, which may then be further refined into usable products such as gasoline, diesel, and various forms of petrochemicals.

As bitumen may not be pumped from the ground in its natural state, the extraction of bitumen from the tar sands may be more complex in some aspects than conventional oil recovery. In at least one extraction process, tar sand deposits are mined using strip mining or open pit techniques. The tar sands are transported to an extraction plant, where heat is applied to the tar sands and the tar sands are agitated, resulting in the separation of the bitumen from the remainder of the tar sands. Although effective, the aforementioned extraction process requires a heat source and energy to power the heat source, which increases the operating costs of the extraction plant.

What is needed, therefore, is a process to remove bitumen from tar sands that may be carried out without the addition of thermal energy from a thermal energy source, thereby reducing operating costs associated with the removal of bitumen from tar sands.

SUMMARY

Embodiments of the disclosure may provide a method for removing bitumen from tar sands. The method may include contacting the tar sands with a hydrocarbon. The method may also include contacting the tar sands including the hydrocarbon with a water soluble silicate. The method may further include separating the tar sands into a liquid portion and a solid portion, the liquid portion including the water soluble silicate and the bitumen. The method may also include separating the water soluble silicate from the bitumen.

Embodiments of the disclosure may further provide a method for removing bitumen from tar sands. The method may include crushing the tar sands in a crusher to form a crushed tar sand. The method may also include contacting the crushed tar sand with a hydrocarbon to form a first mixture. The method may further include contacting the first mixture with a water soluble silicate at ambient temperature to form a second mixture. The method may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion. The method may further include contacting the first mixture with the first liquid portion.

Embodiments of the disclosure may further provide a method for removing bitumen from tar sands. The method may include crushing the tar sands in a crusher to form a crushed tar sand. The method may also include conveying the crushed tar sand to a first mixer. The method may further include contacting the crushed tar sand with a hydrocarbon in the first mixer to form a first mixture. The method may also include conveying the first mixture to a second mixer. The method may further include contacting the first mixture with a water soluble silicate at ambient temperature in the second mixer to form a second mixture. The method may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion. The method may further include feeding the first liquid portion to the second mixer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates a schematic of a system for removing bitumen from tar sands, according to one or more embodiments.

FIG. 2 is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments.

FIG. 3 is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments.

FIG. 4 is a flowchart depicting a method for removing bitumen from tar sands, according to one or more embodiments.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

FIG. 1 illustrates a schematic of a system 100 for removing bitumen from tar sands, according to one or more embodiments of the present disclosure. The tar sands may be removed from the earth at various depths via one or more removal processes. For example, the tar sands at shallow depths (e.g., less than about 70 meters to about 75 meters) may be removed from the earth via mining. The mining of the tar sands may be carried out via strip mining or open pit mining after the mineable areas are cleared of trees, shrubs, and/or other land vegetation. In open pit mining, a layer of earth, referred to as the overburden, may be removed and an open pit is created. Tar sand deposits may be located near the surface of the earth in the open pit and heavy machinery including hydraulic and electrically powered rope shovels may be used to dig up and load the tar sands into trucks or other like transport vehicles for the removal of the tar sands from the open pit.

As illustrated in FIG. 1, the tar sands may be transported from an open pit 102 to the system 100, which may be located at the site of the mining operations, e.g., the open pit 102, or adjacent thereto in one or more embodiments. The present disclosure is not limited thereto, and in other embodiments, the system 100 may be located at a site remote from the mining operations. In yet another embodiment, one or more of the components of the system 100 may be located at one or more remote locations from at least one other component of the system 100, where trucks, or other suitable transport means, may be provided to operatively connect the components of the system 100.

Although not illustrated in detail in the schematic of FIG. 1, the system 100 may include a hopper or like receptacle configured to receive the tar sands removed from the open pit 102 and transported from the transport vehicles. The transported tar sands may be in lump form, where a plurality of lumps of the tar sands may be introduced to the hopper. The hopper may be further configured to funnel or otherwise direct the lumps of tar sands to a crusher 104 adjacent to and, in some embodiments, coupled to the hopper and configured to break, crush, grind, or otherwise reduce the lumped tar sands to a crushed tar sand. In one or more embodiments, the crusher 104 may be a sizer or grinder. The crushed tar sand may be or include a plurality of loose tar sand particles. It will be appreciated that the contactable surface area of the tar sands is increased as the lumped tar sands are reduced in size to loose tar sand particles.

The crushed tar sand may exit the crusher 104 and may be dumped onto or otherwise disposed on a conveyer or like transport device. In the example embodiment illustrated in FIG. 1, the system 100 may include a mixer 106 operatively coupled to the conveyor and configured to receive the crushed tar sand discharged from the crusher 104. Although not illustrated, in at least one embodiment, a storage component (e.g., silo, stockpile, surge bin) may be operatively coupled to the crusher 104 and the mixer 106 and may be configured to store the crushed tar sand prior to the introduction thereof to the mixer 106 in the event of a shutdown or otherwise temporary interruption of the bitumen removal process. In at least one embodiment, the crushed tar sand may be further screened via a screener (not shown) prior to introduction to the mixer 106 in order to remove any oversized material (e.g., rocks, ice, or petrified wood intermixed with the crushed tar sand) not sufficiently crushed in the crusher 104. The removed oversized material may be transported back to the crusher 104 or sent to a waste pile (not shown) depending on the composition of the oversized material.

As illustrated in FIG. 1, the crushed tar sand may be fed from the conveyor into the mixer 106, where the crushed tar sand may be contacted by a solvent to “pre-treat” the crushed tar sand. The mixer 106 may be, for example, a paddle mixer. In other embodiments, the mixer may be a drum mixer, a tumble mixer, and the like. In one or more embodiments, the solvent may be a hydrocarbon supplied by a hydrocarbon source 108 fluidly coupled to the mixer 106. The hydrocarbon source 108 may be located on site or may provide the hydrocarbon to the mixer 106 via one or more pipelines and related conduits. The hydrocarbon source 108 may be, for example, a hydrocarbon well, a hydrocarbon storage tank, or a pipeline. In one or more embodiments, the hydrocarbon may be condensate, gasoline, diesel, or combinations thereof. The hydrocarbon from the hydrocarbon source 108 may be introduced into the mixer 106 automatically or manually. In the event the hydrocarbon is introduced automatically, a control system (not shown) may be provided to monitor, weigh, determine the flow volume of, and distribute the hydrocarbon to the mixer 106 as desired. The amount of hydrocarbon contacting the crushed tar sand may be a function of the weight or volume of the crushed tar sand introduced to the mixer 106.

The hydrocarbon may be introduced to the mixer 106 and may contact the crushed tar sand fed thereto. The contacting of the hydrocarbon with the crushed tar sand, in addition to the mixing or agitation provided by the mixer 106, may result in the separation of a portion of the bitumen from the crushed tar sand. Accordingly, a pre-treated mixture may be formed including the hydrocarbon, the portion of the bitumen removed from the crushed tar sand, and the crushed tar sand.

The system 100 may also include another mixer 110 downstream from and operatively coupled to the mixer 106. The pre-treated mixture may be a slurry in at least some embodiments and may be discharged from the mixer 106 and conveyed to the mixer 110 via a pipeline or like conduit. A slurry pump (not shown) may be utilized to convey the pre-treated mixture from the mixer 106 to the mixer 110. In the mixer 110, the pre-treated mixture may be contacted by an aqueous solution including a water soluble silicate to further separate the bitumen and hydrocarbon solvent from the crushed tar sand. The mixer 110 may be, for example, a paddle mixer. In other embodiments, the mixer 110 may be a drum mixer, a tumble mixer, and the like.

In one or more embodiments, the water soluble silicate may be a sodium silicate. In another embodiment, the water soluble silicate may be a potassium silicate. In yet other embodiments, the water soluble silicate may be a zirconium silicate or a magnesium silicate. The aqueous solution including the water soluble silicate may be supplied by an aqueous solution source 112 fluidly coupled to the mixer 110. The aqueous solution source 112 may be located on site or may provide the aqueous solution to the mixer 110 via one or more pipelines and related conduits. The aqueous solution source 112 may be, for example, an aqueous solution storage tank, a pipeline, a separator discussed in further detail below, or a combination thereof. The aqueous solution source 112 and the conduits fluidly coupled thereto may be insulated.

The aqueous solution including the water soluble silicate may be introduced into the mixer 110 automatically or manually. In the event the aqueous solution including the water soluble silicate is introduced automatically, a control system (not shown) may be provided to monitor, weigh, determine the flow volume of, and distribute the aqueous solution including the water soluble silicate to the mixer 110 as desired. The amount of aqueous solution including the water soluble silicate contacting the pre-treated mixture may be a function of the weight or volume of the pre-treated mixture introduced to the mixer 110.

The aqueous solution including the water soluble silicate may be introduced to the mixer 110 and may contact the pre-treated mixture fed thereto. The aqueous solution including the water soluble silicate at ambient temperature may be introduced to the mixer 110, thereby providing for the absence of a heat source in the system 100. By omitting a heat source and the addition of thermal energy in the system 100, the operating costs and footprint of the system 100 may be reduced. The contacting of the aqueous solution including the water soluble silicate with the pre-treated mixture, in addition to the mixing or agitation provided by the mixer 110, may result in the separation of substantially all of the remaining portion of the bitumen from the pre-treated mixture. Accordingly, a three phase mixture may be formed including the hydrocarbon and the bitumen removed from the pre-treated mixture, the aqueous solution including the water soluble silicate, and the crushed tar sand. In one or more embodiments, the portion of the bitumen removed from the crushed tar sand may be about 90% to about 99% of the bitumen originally present in the crushed tar sand. In another embodiment, the portion of the bitumen removed from the crushed tar sand may be about 95% to about 99% of the bitumen originally present in the crushed tar sand.

The system 100 may further include one or more separators (two shown 114 and 116) configured to separate the three phase mixture. In the embodiment illustrated in FIG. 1, the system 100 may include a liquid-solid separator 114 operatively coupled to the mixer 110 via a pipeline or like conduit and configured to separate the crushed tar sand from the aqueous solution including the water soluble silicate, the hydrocarbon, and the bitumen. Examples of suitable liquid-solid separators 114 may include a gravity separator, a centrifugal separator, a filter, and a hydrocyclone. The separated solid portion (crushed tar sand) may be referred to as “tailings” and may be discharged from the liquid-solid separator 114 and disposed on a shaker (not shown) to further separate any remaining liquids from the solids. The crushed tar sand after removal of the bitumen and any remaining liquids after separation may be a clean sand having an increased crush strength as compared to the tar sand excavated from the open pit 102. The clean sand may be suitable for use in a variety of applications. For example, the clean sand may be used as backfill for the open pit 102 to return the land to a trafficable landscape. In another example, the clean sand may be used as frac sand.

The separated liquid portion from the liquid-solid separator 114 may be transported via a pipeline or like conduit to a liquid-liquid separator 116 fluidly coupled to the liquid-solid separator 114. The liquid-liquid separator 116 may be configured to separate the hydrocarbon and bitumen from the aqueous solution including the water soluble silicate. Examples of suitable liquid-liquid separators 116 may include a gravity separator, a centrifugal separator, a filter, and a hydrocyclone. The aqueous solution including the water soluble silicate may be separated from the hydrocarbon and bitumen and returned to the aqueous solution source 112 and subsequently reintroduced to the mixer 110. In at least one embodiment, the aqueous solution including the water soluble silicate may be separated from the hydrocarbon and bitumen and transported directly back to the mixer 110. The separated hydrocarbon and bitumen may be transported to a storage tank 118 (illustrated in FIG. 1) located in a tank farm or to another processing component or facility for refining purposes.

Although not illustrated, in another embodiment, the three-phase mixture may be separated in a single, three-phase separator, thereby reducing the number of components in the system 100 and further reducing costs and maintenance of the system. The three-phase separator may be configured to separate the three-phase mixture into a solid portion (crushed tar sand), a first liquid portion (aqueous solution including the water soluble silicate) and a second liquid portion (hydrocarbon and bitumen). After separation, each of the separated portions may be directed in the manners disclosed above with respect to the liquid-solid separator 114 and the liquid-liquid separator 116.

Turning now to FIG. 2 with continued reference to FIG. 1, FIG. 2 is a flowchart depicting a method 200 for removing bitumen from tar sands, according to one or more embodiments. The method 200 may include contacting the tar sands with a hydrocarbon, as at 202. The method 200 may also include contacting the tar sands including the hydrocarbon with a water soluble silicate, as at 204. In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. The method 200 may further include separating the tar sands into a liquid portion and a solid portion, as at 206. The liquid portion may include the water soluble silicate and the bitumen. The method 200 may also include separating the water soluble silicate from the bitumen, as at 208. In at least one embodiment, contacting the tar sands with the water soluble silicate may further include contacting the tar sands with at least a portion of the water soluble silicate separated from the bitumen.

In one or more embodiments, the method 200 may also include crushing the tar sands. In one or more embodiments, the hydrocarbon contacting the tar sands may be selected from condensate, diesel, and gasoline. In one or more embodiments, the hydrocarbon contacting the tar sands may be diesel. In one or more embodiments, the method 200 may also include excavating the tar sands from a tar sand deposit located proximal the surface of the earth.

Turning now to FIG. 3 with continued reference to FIG. 1, FIG. 3 is a flowchart depicting a method 300 for removing bitumen from tar sands, according to one or more embodiments. The method 300 may include crushing the tar sands in a crusher to form a crushed tar sand, as at 302. The method 300 may also include contacting the crushed tar sand with a hydrocarbon to form a first mixture, as at 304. The method 300 may further include contacting the first mixture with a water soluble silicate at ambient temperature to form a second mixture, as at 306. The method 300 may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion, as at 308. The method 300 may further include contacting the first mixture with the first liquid portion, as at 310.

In one or more embodiments, the first liquid portion may be the water soluble silicate, and the second liquid portion may include the hydrocarbon and the bitumen. In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. In one or more embodiments, the hydrocarbon may be selected from condensate, diesel, and gasoline.

In one or more embodiments, the method 300 may also include directing the first liquid portion to a storage tank containing the water soluble silicate, and directing the water soluble silicate from the storage tank to a mixer containing the first mixture. In one or more embodiments, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further includes: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator. In at least one other embodiment, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion may be carried out in a three-phase separator.

Turning now to FIG. 4 with continued reference to FIG. 1, FIG. 4 is a flowchart depicting a method 400 for removing bitumen from tar sands, according to one or more embodiments. The method 400 may include crushing the tar sands in a crusher to form a crushed tar sand, as at 402. The method 400 may also include conveying the crushed tar sand to a first mixer, as at 404. The method 400 may further include contacting the crushed tar sand with a hydrocarbon in the first mixer to form a first mixture, as at 406. The method 400 may also include conveying the first mixture to a second mixer, as at 408. The method 400 may further include contacting the first mixture with a water soluble silicate at ambient temperature in the second mixer to form a second mixture, as at 410. The method 400 may also include separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion, as at 412. The method 400 may further include feeding the first liquid portion to the second mixer, as at 414.

In one or more embodiments, the method 400 may also include directing the first liquid portion to a storage tank containing the water soluble silicate, and directing the water soluble silicate from the storage tank to a mixer containing the first mixture. In one or more embodiments, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further includes: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator. In at least one other embodiment, separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion may be carried out in a three-phase separator.

In one or more embodiments, the first liquid portion may be the water soluble silicate, and the second liquid portion may include the bitumen and the hydrocarbon. In one or more embodiments, the water soluble silicate may be selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate. In one or more embodiments, the solid portion may include a clean sand having a greater crush strength than a crush strength of the tar sand prior to the removal of the bitumen therefrom. In one or more embodiments, feeding the first liquid portion to the second mixer further includes feeding the first liquid portion to a storage tank including the water soluble silicate, and feeding the water soluble silicate including the first liquid portion to the second mixer.

The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. 

We claim:
 1. A method for removing bitumen from tar sands, comprising: contacting the tar sands with a hydrocarbon; contacting the tar sands including the hydrocarbon with a water soluble silicate; separating the tar sands into a liquid portion and a solid portion, the liquid portion including the water soluble silicate and the bitumen; and separating the water soluble silicate from the bitumen.
 2. The method of claim 1, wherein the water soluble silicate is selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate.
 3. The method of claim 2, wherein the water soluble silicate is a sodium silicate.
 4. The method of claim 1, further comprising crushing the tar sands.
 5. The method of claim 1, wherein the hydrocarbon is selected from condensate, diesel, and gasoline.
 6. The method of claim 1, wherein the hydrocarbon is diesel.
 7. The method of claim 1, wherein contacting the tar sands with the water soluble silicate further includes contacting the tar sands with at least a portion of the water soluble silicate separated from the bitumen.
 8. The method of claim 1, further comprising excavating the tar sands from a tar sand deposit located proximal the surface of the earth.
 9. A method for removing bitumen from tar sands, comprising: crushing the tar sands in a crusher to form a crushed tar sand; contacting the crushed tar sand with a hydrocarbon to form a first mixture; contacting the first mixture with a water soluble silicate at ambient temperature to form a second mixture; separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion; and contacting the first mixture with the first liquid portion.
 10. The method of claim 9, wherein the first liquid portion is the water soluble silicate, and the second liquid portion includes the hydrocarbon and the bitumen.
 11. The method of claim 10, wherein separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further comprises: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator.
 12. The method of claim 10, wherein the water soluble silicate is selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate.
 13. The method of claim 9, wherein separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion is carried out in a three-phase separator.
 14. The method of claim 9, wherein the hydrocarbon is selected from condensate, diesel, and gasoline.
 15. The method of claim 9, further comprising: directing the first liquid portion to a storage tank containing the water soluble silicate; and directing the water soluble silicate from the storage tank to a mixer containing the first mixture.
 16. A method for removing bitumen from tar sands, comprising: crushing the tar sands in a crusher to form a crushed tar sand; conveying the crushed tar sand to a first mixer; contacting the crushed tar sand with a hydrocarbon in the first mixer to form a first mixture; conveying the first mixture to a second mixer; contacting the first mixture with a water soluble silicate at ambient temperature in the second mixer to form a second mixture; separating the second mixture into a first liquid portion, a second liquid portion, and a solid portion; and feeding the first liquid portion to the second mixer.
 17. The method of claim 16, wherein separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion further comprises: separating the solid portion from a mixture of the first liquid portion and the second liquid portion in a first separator; feeding the mixture of the first liquid portion and the second liquid portion to a second separator; and separating the first liquid portion and the second liquid portion in the second separator.
 18. The method of claim 16, wherein separating the second mixture into the first liquid portion, the second liquid portion, and the solid portion is carried out in a three-phase separator.
 19. The method of claim 16, wherein: the water soluble silicate is selected from sodium silicate, zirconium silicate, magnesium silicate, and potassium silicate; the first liquid portion is the water soluble silicate, and the second liquid portion includes the bitumen and the hydrocarbon; and feeding the first liquid portion to the second mixer further comprises feeding the first liquid portion to a storage tank including the water soluble silicate; and feeding the water soluble silicate including the first liquid portion to the second mixer.
 20. The method of claim 16, wherein the solid portion includes a clean sand having a greater crush strength than a crush strength of the tar sand prior to the removal of the bitumen therefrom. 